Shared files for CSS?

We currently store the CSS file for a master course in Manage Files. When we copy the course, the CSS file copies. No problem. But suppose we want to make a change that affects 100 courses? We did that in some of our programs to take advantage of Daylight. But, tt would be easiest to store the program's CSS file in one place after the initial development is done. But should that be shared files? We do not allow instructors to upload or edit shared files, so that would SEEM to be safe. What do others do? Also, what would happen if an instructor used a page that correctly pointed to the shared-files css as a page template to make a new page in Content? And, obviously, we would need to provide special instructions for course developers to work offline and still see what their pages look like when the CSS is applied.